From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BA65C31E5B for ; Tue, 18 Jun 2019 15:47:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F49121530 for ; Tue, 18 Jun 2019 15:47:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729833AbfFRPrR (ORCPT ); Tue, 18 Jun 2019 11:47:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47316 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729209AbfFRPrQ (ORCPT ); Tue, 18 Jun 2019 11:47:16 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 70AC530860AD; Tue, 18 Jun 2019 15:47:16 +0000 (UTC) Received: from holly.tpb.lab.eng.brq.redhat.com (holly.tpb.lab.eng.brq.redhat.com [10.43.134.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id CC98B176BC; Tue, 18 Jun 2019 15:47:14 +0000 (UTC) From: Miroslav Lichvar To: linux-kernel@vger.kernel.org Cc: swkhack@gmail.com, Miroslav Lichvar , John Stultz , Prarit Bhargava , Richard Cochran , Stephen Boyd , Thomas Gleixner Subject: [PATCH] ntp: Limit TAI-UTC offset Date: Tue, 18 Jun 2019 17:47:13 +0200 Message-Id: <20190618154713.20929-1-mlichvar@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Tue, 18 Jun 2019 15:47:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Don't allow the TAI-UTC offset of the system clock to be set by adjtimex() to a value larger than 100000 seconds. This prevents an overflow in the conversion to int, prevents the CLOCK_TAI clock from getting too far ahead of the CLOCK_REALTIME clock, and it is still large enough to allow leap seconds to be inserted at the maximum rate currently supported by the kernel (once per day) for the next ~270 years, however unlikely it is that someone can survive a catastrophic event which slowed down the rotation of the Earth so much. Cc: John Stultz Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Thomas Gleixner Signed-off-by: Miroslav Lichvar --- kernel/time/ntp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 8de4f789dc1b..65eb796610dc 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -43,6 +43,7 @@ static u64 tick_length_base; #define MAX_TICKADJ 500LL /* usecs */ #define MAX_TICKADJ_SCALED \ (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ) +#define MAX_TAI_OFFSET 100000 /* * phase-lock loop variables @@ -691,7 +692,8 @@ static inline void process_adjtimex_modes(const struct __kernel_timex *txc, time_constant = max(time_constant, 0l); } - if (txc->modes & ADJ_TAI && txc->constant >= 0) + if (txc->modes & ADJ_TAI && + txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET) *time_tai = txc->constant; if (txc->modes & ADJ_OFFSET) -- 2.17.2